For this type of apparatus, there is known an apparatus configured to distinguish between normal breath sounds and abnormal breath sounds, regarding breath sounds detected by an electronic stethoscope or the like. For example, in Patent Literature 1, there is proposed a method of dividing sounds into normal breath sounds and continuous pulmonary adventitious sounds on the basis of local variance values on a spectrum. In Patent Literature 2, there is proposed a method of determining the degree of abnormality of a respiratory state on the basis of the degree of correlation with a preset model. In Patent Literature 3, there is proposed a method of approximating a spectrum shape by using a mixture Gaussian distribution and determining an abnormal breath sound type.